NUCLEAR REACTOR PLANT WITH CORE HOLDING DEVICE AND METHOD FOR EXTERNAL CORE COOLING BY NATURAL CIRCULATING WATER

A nuclear reactor installation includes a reactor pressure vessel and a reactor core in the reactor pressure vessel. A supporting and protective structure supporting the reactor pressure vessel and surrounding the reactor pressure vessel on the bottom and laterally, has a bottom region and a circumferential wall. A core catcher device for the reactor core has a collecting basin for a core melt being installed below the reactor pressure vessel. The collecting basin has a bottom wall and a jacket wall being respectively separated from the bottom region and the circumferential wall of the supporting and protective structure by a spacing gap. Cooling channels are disposed in the spacing gap at the bottom wall and the jacket wall for exterior cooling of the collecting basin with a cooling liquid. Turbulence bodies are disposed in a surface region of the bottom wall for generating a turbulent flow of the cooling liquid flowing from the inside to the outside over the bottom wall toward the jacket wall. There is also a method for starting and maintaining exterior cooling of a core catcher device of a nuclear reactor installation.